Process for treating fibrous materials and resulting products



United States Patent "ice 3,271,101 PROCESS FOR TREATING FIBROUS MATERIALS AND RESULTING PRODUCTS Edward L. Patton, Middlesex, NJ., and Robert D. Lundahl, Hawthorne, N.Y., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Sept. 11, 1961, Ser. No. 137,024

12 Claims. (Cl. 8-120) This invention relates to the treatment of fibrous materials. More particularly, the invention relates to an improved process for treating cellulosic fibrous materials to impart dimensional stability, and to the improved products obtained thereby.

Specifically, the invention provides a new and highly efiicient process for treating cellulosic fibrous materials, and particularly cellulosic textile materials as cotton fibers and fabrics, with an epihalohydrin or material which liberates epihalohydrin to form products having excellent wet crease recovery without undue loss of strength. This process comprises impregnating the desired fibrous material with a caustic solution and exposing the impregnated material to hot vapors composed of water and an epihalohydrin or material which liberates an epihalohydrin, for a short period, e.g., less than minutes, and then washing the treated material. The invention further provides fibrous materials having improved properties which are prepared by the above-described new process.

Nitrogenous resins have been applied to cellulosic textile materials to produce wash-and-wear fabrics. These resins, however, lack the ability to produce an acceptable wet crease recovery. Thus, the conventional thermosetaing resins impart a satisfactory appearance to fabrics which are tumble dried, but fail to eliminate Wrinkles when the fabrics are drip or line dried.

It has been found that cotton fabrics having high wet crease recovery which is durable to repeated launderings can be obtained by treating the fabric with liquid epichlorohydrin or material which liberates epichlorohydrin. This has been accomplished heretofore by a batch process wherein caustic treated fabric is contacted with liquid epichlorohydrin or glycerol dichlorohydrin and the treated fabric cured at room temperature for several hours. This process, however, has certain drawbacks which makes it undesirable for use on a large commercial scale. The cure cycle of several hours, for example, is not entirely suitable for commercial operations. Further, the process is batch operated and there is considerable lack of uniformity in the proper-ties of the resulting products. In addition, properties of the finished product leave much to be desired. It has been found, for example, that the treated fabric suffers considerable loss of strength because of the epichlorohydrin batch treatment, and the product is unsuited for certain applications requiring a high degree of tear and tensile strength. Further, such a process does not permit easy control over the degree of wet crease recovery to be obtained, as well as raises problems of vapor hazard when handling the epichlorohydrin during the mill operations. Finally, this prior known process is so expensive to operate that its use has been restricted to expensive specialty type goods.

We have found that certain of these difficulties can be overcome by using a special technique wherein the caustic impregnated textile material is exposed to vapors of the epihalohydrin or material which liberates epihalohydrins. This process is particularly advantageous in that it can be operated in a continuous and efficient manner and brings about the desired cure in a short cure cycle.

While this vapor procedure represents a considerable improvement over the batch technique, the vapor process still possesses certain disadvantages which place limitation on commercial use. For example, the add-on of the epi- 3,271,101 Patented Sept. 6, 1966 chlorohydrin for a given wet crease recovery is still quite high, there is a problem of keeping the moisture content high enough to maintain the cloth in a reactive condition, the strength loss during the treatment is still more than desired for certain applications, and the dyeability could be improved.

It is, therefore, an object of the invention to provide a new process for treating fibrous materials. It is a further object to provide a new process for treating cellulosic textile materials to impart a high wet crease recovery. It is a further object to provide a new process for imparting high wet crease recovery that can be operated on a continuous manner and will give products having uniform properties. It is a further object to provide an improved, short cure cycle process for treating textile materials with an epihalohydrin. It is a further object to provide a process for treating textile materials with an epihalohydrin which imparts high crease recovery without undue loss of strength. It is a further object to provide a process for textile treatment which gives products having good dyeability. It is a further object to provide a process for textile treatment with epichlorohydrin which permits good control over water content and gives high crease recovery at low resin add on. It is a further object to provide a process for providing new textile materials having improved p-roperties. It is a further object to provide a new and highly economical process for imparting Wet crease recovery to cotton goods. It is a further object to provide new textile materials having improved wet crease recovery. It is a further object to provide paper and Wood products having improved dimensional stability. These and other objects of the invention will be apparent from the following detailed description thereof.

It has now been discovered that these and other objects may be accomplished by the process of the invention which comprises impregnating the desired fibrous material with a caustic solution and exposing the impregnated material to hot vapors composed of a mixture of water and an epihalohydrin or material which liberates an epihalohydrin, for a short period, say less than 5 minutes, and then washing the treated material. It has been found that this new process avoids all of the above-noted difiiculties and provides a highly efficient method for obtaining fibrous materials having improved dimensional stability, particularly when wet. The textile materials obtained by this process, for example, have a high de gree of wet crease recovery which is obtainable even with the use of less epihalohydrin than the previous processes. In addition, the resulting products retain a greater part of the strength than heretofore and possess improved dyeability. Further, the process is operable in a continuous manner and employs very short cure cycles. Particular advantage is found in the fact that the new process gives more favorable conditions for reaction and makes for easier process control. There is, for example, no problem as .to control of water content nor danger from the epichlorohydrin vapors as in the prior known liquid process.

The compounds to be used in the treatment of the textile material include the epihalohydrins and the material which liberate epihalohydrins when in an alkaline medium. The epihalohydrins, which are halo-substituted monoepoxy compounds, may be exemplified by epichlorohydrin, epibr-omohydrin, 2,3-epoxy-2-methyl-l-chloropropane, 2,3-epoxy l-chlorobutane, 2,3-epoxy-l-bromobutane, 2,3-epoxy-l-chloropentane and the like. The materials which liberate epihalohydrins when in an alkaline medium, i.e., materials having a group in place of the 1,2-epoxy group, include the dihalohydrins as 1,3-dichloro-2-hydroxypropane, 1,3-dibromo-Z-hydroxypropane, l,3-dichloro-Z-hydroxybutane, 1,3-dichloro-Z-hydroxypentane, 2-methyl- 1 ,3-dichlo-ro-2- hydroxypropane and the like, and mixtures thereof. Epichlorohydrin is particularly preferred.

In the process of the invention, the material to 'be treated is brought into contact with aqueous caustic solution. The causti employed is preferably sodium hydroxide but potassium hydroxide or other alkali or alkali earth metal hydroxides may be utilized. The strength of the caustic solution may vary but preferred concentrations vary from about 1% to 25% by weight. Within this range, the crease recovery is roughly proportional to the caustic concentration. While the higher concentrations tend to give higher wet crease recovery in a shorter cure period, in some cases they tend to have a more deleterious effect on the strength of the heated fabric. Accordingly, the more preferred concentrations generally range from about 5% to by weight.

The impregnation with the aqueous caustic may be accomplished by any suitable means, such as, for example, by dipping, spraying, padding and the like. It is generally preferred to pass the textile material into and through the aqueous solution as by padding. The amount of wet pick-up will vary with the different cases, but generaly it is preferred to have a wet pick-up varying from about 40% to 100% by weight based on dry fabric. Varying pick-up has little effect on crease recovery. Increasing pick-up of, say, a 10% NaOH solution from 40% to 100% results in gain of about in the crease recovery.

The temperature of the caustic solution as well as the temperature of the textile material to be impregnated may vary, but in general it is preferred to have both at elevated temperature. The efiiciency of the process is thereby improved at higher temperatures.

It is also desirable in some cases to employ wetting agents in the caustic solution to assist in speeding the cure. These agents may be any of the known cationic, anionic or non-ionic materials and may have a great variety of different compositions. Preferred materials include the ionic agents and especially those having a polar structure including a hydrophobic residue and charged ionic radical thereon, such as anionic surface active compounds include alkali metal and nitrogen-base soaps of higher fatty acids, such as potassium and sodium myristate, laurate, palmitate, oleate, stearate, ammonium stearate, etc., as well as the surface-active compounds of the cation-active variety, such as salts of long-chain aliphatic amines and quaternary ammonium bases, such as lauryl amine hydrochloride, stearyl amine hydrochloride, and the like. Examples of the non-ionic agents include the partial esters of polyhydric alcohols and fatty acids, such as the hexitans and hexitide esters as sorbitan monolaurate, hydroxypolyoxyalkylene ethers of the above-described partial esters as the polyethylene glycol ethers of sorbitan monolaurate, the hydroxypolyoxyalkylene ethers of phenols as the reaction product of ethylene oxide and .bis-phenol-A and the like and mixtures thereof. These materials are preferably employed in amounts varying from about .l% to by weight, and still more preferably from 1% to 5% by Weight.

The material impregnated with the caustic solution is then exposed to the hot vapors comprising a mixture of water and an epihalohydrin or material which liberates an epihalohydrin. The mixture should contain at least 10% by weight of Water, and preferably 10% to 80% by weight of water and 90% to 20% by weight of epihalohydrin or material which liberates epihalohydrin. For use in treating textiles, the hot vapor preferably contains at least and preferably 80% by weight of the epihalohydrin or material which liberates epihalohydrins component, and still more preferably is a mixture which exists at a temperature between 180 F. and 250 F.

The preferred vapor mixture of water and epichlorohydrin is the constant boiling vapor composition at 190 F. at 760 mm. and has a composition of about 76% by Weight of epiohlorohydrin and 24% by weight of water. For example, this vapor can be generated by boiling a liquid mixture containing 10 to weight epichlorohydrin.

The length of time for exposing the impregnated fibrous material to the hot vapors will vary depnding on the degree of crease recovery desired and the specific mechanical construction of the said material. Generally, crease recovery increases with time up to about 2 or 3 minutes. After that .it tends to level off. The period of exposure in all cases will not be more than a few minutes, and preferably between 15 seconds to about 5 minutes. Using water-epichlorohydrin vapors and caustic solutions of concentration of 1% to 25% preferred reaction times vary from about 30 seconds to 3 minutes.

A great variety of different techniques may be used to expose the impregnated fibrous material to the hot vapors. The impregnated fibrous material, for example, may be hung or suspended in the presence of or continuously passed through vapors obtained by refluxing the water-epihalohydrin (or material liberating epihalohydrin) mixture. In another technique, the impregnated material may be hung in the presence of or continuously passed through a stream of hot vapors formed by passing live steam into boiling epihalohydrin and the steam used as a carrier for the epihalohydrin or material liberating the epihalohydrins.

After the impregnated material is removed from the curing zone, it may then be washed to remove any excess epihalohydrin or other material, dried and then used immediately in the intended commercial applications. Washing is preferably accomplished by use of water or Water and detergents and then drying at temperatures ranging from about 20 C. to 125 C.

The textile material obtained by the above-described process will have the same appearance and feel as before the treatment but will demonstrate excellent wet crease recovery and improved hand. The material will also have satisfactory strength and non-chlorine retention properties.

The paper and Wood products treated as above will demonstrate improved dimensional stability.

The products treated as above may then be utilized for any of the intended applications. The textile materials may be 'used in the manufacture of dresses, drapes, upholsteries, shoe fabrics, carpets, coats, shirts, uniforms, shoes, towels, cords, construction fabrics and the like. The use will, in many cases, determine the amount of the epihalohydrin or material liberating the epihalohydrin to be applied to the textile material. The paper treated by the process of the invention may be used in the preparation of improved wrapping materials, containers, cards and the like. The wood products may be used in conventional structural applications and the like.

The above-described process may be utilized for the treatment of any cellulosic fibrous material. This includes paper, wood and textile materials. The textile materials may be woven and non-woven fabrics, threads, gauze, yarn, cord, string, netting, and the like. The material may also be pretreated, e.g., mercerized, dyed and resin-treated. By cellulosic is meant material which has a part, and preferablyat least 40% derived from cellulosic materials, such as natural cellulose such as cotton, linen, and the like, and other as viscous, cuprammonium rayon, and other regenerated cellulose, as well as mixtures of any of the foregoing as well as mixtures with wool, synthetics as fibers derived from acrylonitrile (Odom-% acrylonitrile polymer), vinylidene cyanide polymers, polyamides (nylon-super polyamides), polyester-polyamides, polymers prepared from corn protein and formaldehyde, as well as copolymers of the above monomers as, for example, Acrilan (85% acrylonitrile and 15% vinyl acetate), Dynel (60% vinyl chloride and 40% acrylonitrile), Saran (85% vinylidene chloride and 15% vinyl chloride), and other synthetic fabrics or fibers prepared from polyalkylenes as polyethylene, polypropylenes, polyurethanes, mineral fibers (Fiberglas), and Alginic materials as Aliginate rayon.

The preferred materials to be employed in the process include those textile materials containing at least 30% cellulosic materials and preferably those derived from cotton and rayon.

To illustrate the manner in which the invention may be carried out, the following examples are given. It is to be understood, however, that the examples are for the purpose of illustration and the invention is not to be regarded as limited to any of the specific materials or conditions recited therein.

The wrinkle recovery values reported in the examples were determined by the Tentative Method of Test for Recovery of Textile Fabrics From Creasing, Using the Verticle Strip Apparatus, ASTM Designation D1295- 53T (reported as sum of average warp and fill measurements), and textile strength values were determined by Federal Specification CCC-T-l916, Instron Tensile Testing Machine Method 5100. ,All tests were carried out at 6S: ;2% relative humidity and 70: :2 F.

The wet crease recovery values were determined by soaking the fabric in water for 5 minutes and then blotting before testing.

Example I.This example illustrates the superior results obtained by using the process of the invention for treating cotton print fabric.

Bleached 80 x 80 count cotton print cloth was impregnated with an aqueous solution of 10% NaOH at a wet pick-up of 100% (based on weight of dry fabric) using a Morrison Laboratory 3-roll padder. The impregnated fabric is introduced continuously into a chamber containing hot (190-192 F.) vapors of an epichlor'ohydrin-water azeotrope composed of about 76% epi and 24% by weight of water. The fabric is passed over a series of rollers through the hot vapor as to permit a contact time of one minute. The fabric is then rinsed in hot running tap water and hung at room temperature to dry.

The finished fabric had an excellent white hue and excellent drip drying properties. With a one minute contact time the tensile strength (filling direction) of the treated fabric was 29 pounds as compared to 43 pounds for the untreated control While the Elmendorf tear strength was 320 grams and 448 grams, respectively. The treated fabric gave a wet crease recovery angle of 291 (warp+ fill). The untreated control had a wet crease recovery angle of 143 C.

Example II.Example I was repeated using 10% by weight NaOH, 100% wet pick up, 1 minute reaction time but the temperature of the caustic pad bath was modified as shown in the table. The wet crease recovery values and tensile strength values are shown in the table.

Wet Crease Recovery Angle, Degrees Filling Tensile Strength, Pounds Temperature F 27 27 170- 28 Untreated control 42 was a blend of 60% cotton and 40% nylon.

Percent Wet Crease Reaction Time (min) Add-On Recovery Angle Example IV.Example I was repeated with the exception that the fabric was impregnated at ambient temperature with a 7.5% NaOH solution. The cure time was also varied as shown in the table below.

Wet crease recovery Reaction time (min.): n 1 degrees Example V.Example I was repeated with the exception that the fabric was impregnated at ambient temperature with a 5.0% NaOH solution. The cure time was also varied as shown in the table below.

Wet crease recovery Reaction time (min.): angle, degrees1 Example Vl.Example I was repeated with the exception that the percent wet pick-up of the caustic solution on the fabric was varied from 40% to 100% The wet crease recovery angles are shown in the following table.

Wet crease recovery Percent wet pick-up: angle, degrees Example VII .-Example I was repeated with the exception that the impregnated cotton fabric was suspended in a heated chamber and the hot w'ater-epichlorohydrin azeotrope vapors were swept into the chamber and in contact with the suspended impregnated fabric. Related results are obtained.

Example VIII.Examples I to VH are repeated with the exception that 0.1% of lauryl sulfate as a Wetting agent is added to the aqueous NaOH solution before the impregnation. This addition reduces the cure time needed to reach certain crease recovery value.

Example IX .This example illustrates the use of the process of the invention for treating rayon fabric.

Rayon fabric was impregnated with an aqueous solution of 5% by weight NaOH at a wet pick-up of about 80% using a Morrison Laboratory 3-roll padder. Samples of the rayon fabric were suspended in a reaction chamber containing hot vapors of water-epichlorohydrin ezeotrope for a period of about two minutes. Vapor temperature was about F. The fabric was then rinsed in hot water and hung at room temperature to dry. The resulting fabric had excellent drip drying properties.

Example X .-Example I is repeated using a fabric which Related results are obtained.

Example XI.Example I is repeated using a fabric which was a blend of 70% cotton and 20% wool. Related results are obtained.

Example XlI.Example I was repeated using waterepichlorohydrin azeotrope vapor at 200 F. and a one minute cure cycle. Related results are obtained.

Example XIII.Example I was repeated using a concentration of aqueous NaOH of 2.5%. Related results are obtained.

Example XI V.-Example VII is repeated with the exception that the hot water epichlorohydrin vapors are replaced with hot vapors of a mixture of water and glycerol dichlorohydrin. Related results are obtained. Example X V.Example I is repeated with the exception that the impregnated cotton fabric is passed into a chamber containing hot vapors of a mixture of 50% water and 50% epichlorohydrin. Related results are obtained.

Example X VI .-Example I is repeated with the exception that the impregnated cotton fabric is passed into a chamber containing hot vapors of a mixture of 30% water and 70% epichlorohydrin. Related results are obtained.

Example X VII.-Example VII is repeated with the exception that unbleached kraft paper is employed in place of the cotton fabric. Paper having improved dimensional stability is obtained.

Example X VIII.Example VII is repeated with the exception that strips of pine wood are employed in place of the cotton fabric. Wood products having improved dimensional stability are obtained.

We claim as our invention:

1. A process for treating cellulosic fibrous materials to impart dimensional stability thereto which comprises impregnating the fibrous material with a 1% to 25% aqueous caustic solution and exposing for a period of from about seconds to 3 minutes the resulting wet impregnated material to hot vapors of a mixture of water and a member of the group consisting of epihalohydrins and materials which liberate epihalohydrins in an alkaline medium, said mixture containing at least 10% by weight of water,

2. A process as in claim 1 wherein the vapor mixture is the water-epichlorohydrin azeotrope which boils at 1895 F. at 760 mm.

3. A process as in claim 1 wherein the material employed in the form of hot vapors is a mixture of water and glycerol dichlorohydrin.

4. A process as in claim 1 wherein the fibrous material is cotton fabric.

5. A process as in claim 1 wherein the fibrous material is paper.

6. A process as in claim 1 wherein the fibrous material is wood.

7. A process as in claim 1 wherein the aqueous caustic solution used to impregnate the textile material also contains small amount of a wetting agent.

8. A process for treating cellulosic, textile materials containing at least 40% by weight of a cellulosic material to improve the drip dry properties which comprises impregnating the material with a 1% to 25% by weight aqueous NaOH solution and a 40% to wet pickup and then exposing the impregnated material to vapors of a water-epichlorohydrin azeotrope for a period of 15 seconds to five minutes, removing the treatment material, washing and drying.

9. A process as in claim 8 wherein the temperatures of the water-epichlorohydrin vapor mixture varies from about and 250 F.

10. A process as in claim 8 wherein the textile material is impregnated with the NaOH solution at a temperature between 15 C. and 40 C.

11. A process'as in claim 8 wherein the textile material is cotton.

12. A process as in claim 8 wherein the textile material is rayon.

References Cited by the Examiner UNITED STATES PATENTS 1,594,532 8/1926 Ross et al 117106 1,863,208 6/1932 Schorger. 2,109.295 2/1938 Lawrie 812O X 2,985,501 5/1961 Gagarine 8-116 X OTHER REFERENCES Organic Chemistry: Whitmore, August 1937 (four lines from the bottom of page 378 pertinent).

J. TRAVIS BROWN, Acting Primary Examiner.

Examiners. 

1. A PROCESS FOR TREATING CELLULOSIC FIBROUS MATERIALS TO IMPART DIMENSIONAL STABILITY THERETO WHICH COMPRISES IMPREGNATING THE FIBROUS MATERIAL WITH A 1% TO 25% AQUEOUS CAUSTIC SOLUTION AND EXPOSING FOR A PERIOD OF FROM ABOUT 15 SECONDS TO 3 MINUTES THE RESULTING WET IMPREGNATED MATERIAL TO HOT VAPORS OF A MIXTURE OF WATER AND A MEMBER OF THE GROIP CONSISTING OF EPIHALOHYDRINS AND MATERIALS WHICH LIBERATE EPIHALOHYDRINS IN AN ALKALINE MEDIUM, SAID MIXTURE CONTAINING AT LEAST 10% BY WEIGHT OF WATER. 